ASoC: Only run power_check() on a widget once per run

Some widgets will get power_check() run on them more than once during a
DAPM run, most commonly due to supply widgets checking to see if their
consumers are powered up. It's wasteful to do this so cache the result
of power_check() during a run. For one system I tested this on I got an
improvement of:

           Power    Path   Neighbour
Before:    106      970    1186
After:     69       727    905

from this.

Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>

1 files changed, 13 insertions, 2 deletions

diff --git a/sound/soc/soc-dapm.c b/sound/soc/soc-dapm.c
index e6a08822227e..c39146d435e2 100644
--- a/sound/soc/soc-dapm.c
+++ b/sound/soc/soc-dapm.c
@@ -787,10 +787,17 @@ EXPORT_SYMBOL_GPL(dapm_reg_event);
 
 static int dapm_widget_power_check(struct snd_soc_dapm_widget *w)
 {
+        if (w->power_checked)
+                return w->new_power;
+
         if (w->force)
-                return 1;
+                w->new_power = 1;
         else
-                return w->power_check(w);
+                w->new_power = w->power_check(w);
+
+        w->power_checked = true;
+
+        return w->new_power;
 }
 
 /* Generic check to see if a widget should be powered.
@@ -1322,6 +1329,10 @@ static int dapm_power_widgets(struct snd_soc_dapm_context *dapm, int event)
 
         memset(&card->dapm_stats, 0, sizeof(card->dapm_stats));
 
+        list_for_each_entry(w, &card->widgets, list) {
+                w->power_checked = false;
+        }
+
         /* Check which widgets we need to power and store them in
          * lists indicating if they should be powered up or down.  We
          * only check widgets that have been flagged as dirty but note